This invention is related generally to field emitter arrays.
Field emitter arrays (FEAs) generally include an array of field emitter devices. Each emitter device, when properly driven, can emit electrons from the tip of the device. Field emitter arrays have many applications, one of which is in field emitter displays (FEDs), which can be implemented as a flat panel display. In addition to flat panel displays, FEAs have applications as electron sources in microwave tubes, X-ray tubes, and other microelectronic devices.
FIG. 1 illustrates a portion of a conventional FEA. The field emitter device shown in FIG. 1 is often referred to as a xe2x80x9cSpindt-typexe2x80x9d FEA. It includes a field emitter tip 12 formed on a semiconductor substrate 10. Refractory metal, carbide, diamond and silicon tips, silicon carbon nanotubes and metallic nanowires are some of the structures known to be used as field emitter tips 12. The field emitter tip 12 is adjacent to an insulating layer 14 and a conducting gate layer 16. By applying an appropriate voltage to the conducting gate layer 16, the current to the field emitter tip 12 passing through semiconductor substrate 10 is controlled.
FEAs in many prior art designs are susceptible to failure due to gate-to-substrate short circuiting and gate to tip arcing. Typically, failure occurs from (i) an overvoltage on the gate and bulk breakdown of the insulating layer 14 that allows current to punch through or flash over the insulating layer 14 of the gate and creates a high current arc that destroys the entire device or (ii) an overvoltage on the gate that causes an arc to develop between the grid and tip.
A large number of field emitter tips are typically supplied current by a single conducting gate layer. Thus, when short circuit failure occurs, all the emitter tips corresponding to a particular gate layer are affected, and failure is catastrophic.
In accordance with one aspect of the present invention, there is provided a field emitter device disposed over a semiconductor substrate. The field emitter device comprises: at least one field emitter tip disposed over the substrate; a conducting gate electrode layer disposed over the substrate; a protective electronic component disposed over and integral to the substrate and electrically connecting the conducting gate electrode layer to the substrate such that if the conducting gate electrode layer experiences a voltage greater than a breakdown voltage of the field emitter device, the protective electronic component conducts current between the conducting gate electrode layer and the substrate.
In accordance with another aspect of the present invention, there is provided a method of forming a field emitter device formed over a semiconductor substrate. The method comprises: forming at least one field emitter tip over the substrate; forming a conducting gate electrode layer over the substrate; forming a protective electronic component over and integral to the substrate and electrically connecting the conducting gate electrode layer to the substrate such that if the conducting gate electrode layer experiences a voltage greater than a breakdown voltage of the field emitter device, the protective electronic component conducts current between the conducting gate electrode layer and the substrate.